JOHANNESBURG: Fifty rioting inmates and nine prison guards were injured at a South African maximum security lock-up after prisoners went on the rampage and set their cells alight, police said Tuesday.

Police and prison forces moved in using stun grenades after the inmates of a section housing 750 men torched cells and barricaded themselves in a courtyard of the prison in the Free State province.

"There were 50 inmates who got injured and nine prison warders who also got injured. But no one died and no-one was shot," police spokesman Peter Kareli told AFP.

The injuries were due to a stampede after officers moved in, he said.

"The inmates locked themselves in the courtyard. One of the doors was still burning and it was very hot so we couldn't actually open it and go inside," Kareli told AFP.

"We joined forces and tactically moved in and climbed over all those high walls so that we could reach the other side of the inmates."

The officers were forced to use torchlight after the prisoners broke the electrical light globes, he said.

"There was no light so we had to use torches to see actually what is taking place," he said.

The riot broke out late Monday afternoon at the Groenpunt prison and two warders were injured after the prisoners pelted them with debris from a wall that was damaged.

Three offices and a tuckshop were destroyed and a gymnasium and six cells damaged.

The riot had been contained by 1:30 am Tuesday and the inmates searched and handmade weapons seized, said Kareli.

"Everything is under control, we managed to get every inmate into their cells and everything is actually quiet at the present moment."

In November, police rescued a prison doctor who had been held hostage for 20 hours by two inmates who demanded better food at the privately operated Mangaung maximum security prison near Bloemfontein.

The doctor was freed unharmed.